Tautomers disaccharides

The decarbonylation reaction is not confined to aldehydes, but also embraces those compounds that have aldehyde tautomers. Thus, both carbohydrates and allylic alcohols can be decarbonylated. When glucose is allowed to react with frani -[RhCl(CO)(PPh3)2] in A -methylpyrrolidin-2-one, decarbonylation occurs and arabinitol is formed with retention of configuration. The decarbonylation of fructose to arabinitol is complicated by the simultaneous dehydration to furfinyl alcohol, which is the major product. Analogous reactions occur with lower carbohydrates in the limit, glycolaldehyde is decarbonylated to methanol. Aldose derivatives can also be converted to their C i analogues, but the yields are only about half of those obtained with the parent aldoses. Disaccharides usually give better yields. 

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